The present invention relates to communication systems, in particular, a code division multiple access communication system.
System xe2x80x9coptimizationxe2x80x9d refers to an activity of adjusting communication system operating parameters such that an optimal performance of the communication system is achieved. In a code division multiple access (CDMA) communication system, such parameters include cell site pilot power, neighbor lists for each sector, cell site access window (size), antenna down-tilt angles, and hand-off parameters. Handoff parameters include threshold-add (T-Add) and threshold-comparison (T-Comp) among other parameters. A mobile station measures a pilot signal strength and reports the result to the base station. The base station compares the pilot strength against a T-Add; if the value is above T-Add, the base station that transmitted the pilot signal is added to an active or candidate list in the mobile station. If the measured pilot strength value is above another pilot signal strength value already in the active or candidate list as much as the T-Comp value, the new base station replaces base station already in the list. One or more values of such parameters are stored in a database in the communication system.
A complex task of optimizing multiple interrelated variables starts during the initial system design phase. The next phase is an intense field optimization which starts after equipment and software are installed. Finally, after commercial operation starts, the system operators continue with an on-going optimization activity to adapt to changes in the coverage areas. Such a change may include a change in average number of users in the area as the result of the market expansions.
Currently the system optimization tasks involve heavy usage of iterative xe2x80x9cdrive-testingxe2x80x9d, an activity where engineers use a test subscriber mobile unit and drive by while making calls and collecting data. The data collected is analyzed to determine and resolve problems, and identify areas of potential improvement. The cost of optimization is proportional to the number of cell sites and sectors in the coverage area being optimized. The performance metrics for which a system is optimized usually includes: satisfactory coverage area, maximum access rate, minimal dropped calls, and best audio quality. After each run, the parameters of the communication system are changed while monitoring the effects of the changes. If the parameters with their new values provide an acceptable system performance, the new values for the parameters are stored in the system for operational use.
Changing database parameters is intrusive, and involves risk of entering erroneous data. Since all mobile stations are effected by the parameters, an erroneous entry may result in an overall system outages and shutdown. Moreover, determining new database parameters takes time. Modifying parameters via a drive testing involves driving through a route repeatedly until the desired results are achieved. Only one xe2x80x9csetxe2x80x9d of parameters may be modified at a time.
Therefore, there is a need for a method and apparatus that easily optimize the parameters of a communication system.